The data system tracks student, teacher and administrator performance year to year but has barely gotten off the ground. Other states' systems improve student performance and hold schools accountable.

California's chance to receive hundreds of millions of federal educational dollars may rest heavily on an obscure and long-neglected piece of education infrastructure: a statewide data system that tracks students, teachers and administrators year to year.

Such education systems are expensive, complex and do not win elections for politicians. But experts say they are essential to learn how much of the nearly $60 billion that California spends on K-12 education makes a difference, a fact that student achievement tests only hint at.

Last month, California rolled out the first component, a student database known as CalPADS. It will eventually make it possible to measure what works and what doesn't in classrooms throughout the state. The second major component, a teacher and administrator database known as CalTIDES, will not come online until 2011.

Though still in its infancy, the state's data system has had a rocky history. The project was first conceived in the 1980s, but has been stalled repeatedly by infighting among state agencies and a lack of political support. Already overdue and over budget, it lacks many of the key components in place in other states such as Texas and Florida.

On Friday, the state Legislature passed a bill that removed one of the system's key limitations -- it sets aside a 2006 state law that, at the insistence of teachers unions, prevented California from using the system to evaluate teachers based on the academic gains of their students.

Experts say that identifying the most effective and least effective teachers is one of the most important factors in improving education, and the Obama administration has said that California would be ineligible for $4.35 billion in competitive federal education grants unless it changed the law.

But education officials say that Friday's legislative fix does little to make California more competitive for the federal money, known as Race to the Top funds. To improve the state's chances, Gov. Arnold Schwarzenegger and several legislators have proposed a sweeping education reform bill that, among other things, seeks to hold teachers accountable for the performance of their students.

So far, few in Sacramento have championed the proposal, and the Democrat-controlled Legislature is facing pressure from the powerful teachers unions to delay the bill, education officials say.

David Sanchez, president of the California Teachers Assn., made his position clear at a summer meeting with his membership.

"Paying and evaluating teachers based on a single test score does not improve student learning and does not help attract and retain quality teachers in lower-performing schools," Sanchez said.

"And we will not stand for it."

Disorganized data

California has long been awash in educational data. The state Department of Education alone has 125 separate databases, including those that track student test scores, national origin and school finances.

But for all that data, the state cannot answer many basic questions about public education: Which high school classes are best at preparing students for success in college? Do the hundreds of millions of dollars spent annually on training actually make for better teachers? Which credentialing programs prepare the most effective educators?

For the most part, officials say, nobody knows.

David Gordon, the superintendent for Sacramento County schools, recalls a discussion in 1983 over unifying the databases to make it easier to measure the effectiveness of education reforms.

For two decades, the idea has been popular among reformers and policy wonks, but never received political support or funding.

In the meantime, other states developed data systems that have allowed them to improve student performance, hold schools accountable and spend education dollars more efficiently.

California was spurred into action in 2002, when the No Child Left Behind law required the state to collect new data. The Legislature approved CalPADS that year with little opposition. It was projected to cost $6 million.

In fact, the student database has taken seven years and tens of millions of dollars to build -- the exact figures are in some dispute.

Many attribute the project's delays to the Department of Finance, which one study said used "100 ways of saying no" to slow the project. Finance officials have fought bitterly with the education department on the scope of the system and who would control access to the data.

H.D. Palmer, spokesman for the finance department, acknowledged his department's concerns about privacy and costs over the years. But once the system was approved, "in no way, shape or form have we been an impediment to providing the funds to build the system."

Even today, the two departments have dramatically different estimates for the pricetag: Finance puts it at more than $100 million, including ongoing costs; the Department of Education says one-time development costs were $24 million.